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Introduction

At the core of any application in Microsoft Power Platform and Dynamics 365 lies its data structure—defined by entities (now known as tables in Dataverse). While Microsoft provides a rich set of standard tables, real business needs often require the creation of custom entities to manage unique business processes and data models.

This article provides an in-depth look into custom entity creation and defining relationships between those entities in Microsoft Dataverse, the underlying data platform that powers model-driven apps, Power Apps, and Dynamics 365. Whether you’re building a custom CRM system, an inventory tracking app, or an HR onboarding solution, understanding how to create custom tables and define relationships is foundational.

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What Is a Custom Entity?

In Dataverse, an entity (or table) is a structured set of fields that stores data. A custom entity is one you create to model business-specific data not covered by standard entities like Contact, Account, or Lead.

Examples:

• Invoice
• Support Ticket
• Employee Certification
• Asset Location History

Creating custom entities allows organizations to design applications around their own logic and workflows rather than adapting to pre-built models.

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Creating a Custom Entity (Table)

You can create custom entities using:

• Power Apps Maker Portal (preferred method)
• Solution Explorer in Power Platform
• Classic Solution Designer (for legacy scenarios)

Step-by-Step: Creating a Custom Table in Power Apps

1. Go to Power Apps (https://make.powerapps.com)
2. Navigate to Dataverse > Tables
3. Click “+ New table”
4. Provide:
   • Display Name: e.g., “Asset”
   • Plural Name: e.g., “Assets”
   • Name (Schema Name): auto-generated (new_asset)
   • Optional: Select primary column, table type (standard/custom activity), etc.
5. Click Create

Now you can begin adding columns (fields) and customizing the table.

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Defining Columns (Fields)

Each entity/table has a primary column (like “Name” or “Title”), and you can define additional columns:

Common Column Types:

• Text (Single Line, Multi-line)
• Number (Whole, Decimal, Currency)
• Date/Time
• Choice (Option Set)
• Lookup (Relationship to another table)
• Boolean
• File or Image

Best Practices:

• Use meaningful names (certification_date, project_owner_id)
• Use choices for values with limited options
• Enable auditing for important fields
• Use field security profiles to protect sensitive data

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Understanding Relationships

Once you’ve created custom entities, you can relate them to each other and to standard tables.

Three Types of Relationships:

Relationship Type	Description	Example
1:N (One-to-Many)	One record in table A can be associated with many records in table B	One account has many contacts
N:1 (Many-to-One)	Many records in table A relate to one record in table B	Many invoices linked to one customer
N:N (Many-to-Many)	Records in table A can relate to multiple records in table B and vice versa	Employees can have multiple certifications, and a certification can apply to many employees

Creating Relationships:

1. Open the custom table
2. Go to the Relationships tab
3. Click + New relationship
4. Choose type: 1:N, N:1, or N:N
5. Select the target table
6. Configure relationship behavior (more on this later)

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Relationship Behavior Settings

When defining relationships, you can specify behavior types that control cascading effects:

Options Include:

• Parental: Changes cascade from parent to child (e.g., delete, assign)
• Referential: Maintains link but no cascading changes
• Configurable Cascading: Define custom behavior for assign, share, delete, etc.

Example:

If you delete a Project, should all related Tasks be deleted as well?

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Lookup Columns

Creating a lookup column is the most common way to establish a relationship in a form.

How It Works:

• A lookup field is essentially a foreign key.
• When creating a column, choose Data Type = Lookup
• Select the related table (e.g., Account, Project, etc.)

This allows users to select related records through a drop-down in forms.

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Using Subgrids and Navigation

Once relationships are set up, you can use subgrids and navigation tiles to show related records in forms.

Examples:

• Show all Orders on an Account form
• Display a list of Notes related to a Case
• Navigate from an Employee record to associated Certifications

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Business Scenarios

Let’s explore how relationships and custom entities work together in real-world apps.

Scenario 1: Asset Management

Custom Tables:

• Asset
• Location
• Maintenance Log

Relationships:

• Asset N:1 Location (each asset belongs to one location)
• Asset 1:N Maintenance Log (each asset has multiple logs)

This setup allows tracking where assets are and their maintenance history.

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Scenario 2: Employee Onboarding

Custom Tables:

• Employee
• Onboarding Checklist
• Training Session

Relationships:

• Employee 1:N Checklist
• Employee N:N Training (via an intermediate join table)

This model supports tracking tasks per employee and managing who attended which training sessions.

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Custom Activity Entities

If your custom entity represents an action rather than a static record (like a meeting or task), you can create a custom activity entity.

Features:

• Appears in the Activity Timeline
• Has To/From, Start/End times
• Supports activity parties (multiple participants)

Use Cases:

• Service Visit
• Site Inspection
• Delivery Appointment

Enable this in the entity settings by toggling “Define as an activity”.

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Best Practices for Custom Entity and Relationship Design

1. Prefix names with your org or solution name (abc_invoice)
2. Avoid modifying standard entities unless absolutely necessary
3. Document entity relationships clearly
4. Use managed solutions for production environments
5. Keep relationships logical and meaningful (avoid unnecessary N:N)
6. Consider performance implications for complex N:N relationships
7. Utilize icons and colors to distinguish custom tables in apps

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Using Solutions for Deployment

Always create entities and relationships within a solution to package and move them between environments (Dev → Test → Prod).

Benefits:

• Easy versioning
• Track dependencies
• Export/import customizations

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Limitations to Be Aware Of

• Lookup fields can slow down forms if overused
• N:N relationships are harder to manage with advanced business logic
• Only one primary name field per table
• System-generated relationships are harder to delete once used

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Integration with Forms and Views

After creating entities and relationships:

• Customize forms to include lookup fields or subgrids
• Design views to filter based on related records
• Use Power Automate to automate relationship-based logic

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Relationship and Entity Security

• Use security roles to control who can access which entities
• For lookup fields, users must have permission on both sides of the relationship
• Apply field-level security where needed (e.g., salary on an Employee table)

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Reporting on Custom Entities

• Custom tables are available in Power BI, Excel Online, and Power Apps reports
• Relationships can be used in Dataverse views and Power BI data models for joining data

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